server/config: add mechanism to update template

instead of exposing handlebars itself, offer a register_template and
a render_template ourselves.

render_template checks if the template file was modified since
the last render and reloads it when necessary

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/bin/proxmox-backup-proxy.rs

@@ -1,5 +1,5 @@
 use std::sync::Arc;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use anyhow::{bail, format_err, Error};
 use futures::*;
@@ -53,6 +53,10 @@ async fn run() -> Result<(), Error> {
     config.add_alias("css", "/usr/share/javascript/proxmox-backup/css");
     config.add_alias("docs", "/usr/share/doc/proxmox-backup/html");
 
+    let mut indexpath = PathBuf::from(buildcfg::JS_DIR);
+    indexpath.push("index.hbs");
+    config.register_template("index", &indexpath)?;
+
     let rest_server = RestServer::new(config);
 
     //openssl req -x509 -newkey rsa:4096 -keyout /etc/proxmox-backup/proxy.key -out /etc/proxmox-backup/proxy.pem -nodes

src/server/config.rs

@@ -1,9 +1,13 @@
 use std::collections::HashMap;
-use std::path::{PathBuf};
-use anyhow::Error;
+use std::path::PathBuf;
+use std::time::SystemTime;
+use std::fs::metadata;
+use std::sync::RwLock;
 
+use anyhow::{bail, Error, format_err};
 use hyper::Method;
 use handlebars::Handlebars;
+use serde::Serialize;
 
 use proxmox::api::{ApiMethod, Router, RpcEnvironmentType};
 
@@ -12,21 +16,20 @@ pub struct ApiConfig {
     router: &'static Router,
     aliases: HashMap<String, PathBuf>,
     env_type: RpcEnvironmentType,
-    pub templates: Handlebars<'static>,
+    templates: RwLock<Handlebars<'static>>,
+    template_files: RwLock<HashMap<String, (SystemTime, PathBuf)>>,
 }
 
 impl ApiConfig {
 
     pub fn new<B: Into<PathBuf>>(basedir: B, router: &'static Router, env_type: RpcEnvironmentType) -> Result<Self, Error> {
-        let mut templates = Handlebars::new();
-        let basedir = basedir.into();
-        templates.register_template_file("index", basedir.join("index.hbs"))?;
         Ok(Self {
-            basedir,
+            basedir: basedir.into(),
             router,
             aliases: HashMap::new(),
             env_type,
-            templates
+            templates: RwLock::new(Handlebars::new()),
+            template_files: RwLock::new(HashMap::new()),
         })
     }
 
@@ -67,4 +70,52 @@ impl ApiConfig {
     pub fn env_type(&self) -> RpcEnvironmentType {
         self.env_type
     }
+
+    pub fn register_template<P>(&self, name: &str, path: P) -> Result<(), Error>
+    where
+        P: Into<PathBuf>
+    {
+        if self.template_files.read().unwrap().contains_key(name) {
+            bail!("template already registered");
+        }
+
+        let path: PathBuf = path.into();
+        let metadata = metadata(&path)?;
+        let mtime = metadata.modified()?;
+
+        self.templates.write().unwrap().register_template_file(name, &path)?;
+        self.template_files.write().unwrap().insert(name.to_string(), (mtime, path));
+
+        Ok(())
+    }
+
+    /// Checks if the template was modified since the last rendering
+    /// if yes, it loads a the new version of the template
+    pub fn render_template<T>(&self, name: &str, data: &T) -> Result<String, Error>
+    where
+        T: Serialize,
+    {
+        let path;
+        let mtime;
+        {
+            let template_files = self.template_files.read().unwrap();
+            let (old_mtime, old_path) = template_files.get(name).ok_or_else(|| format_err!("template not found"))?;
+
+            mtime = metadata(old_path)?.modified()?;
+            if mtime <= *old_mtime {
+                return self.templates.read().unwrap().render(name, data).map_err(|err| format_err!("{}", err));
+            }
+            path = old_path.to_path_buf();
+        }
+
+        {
+            let mut template_files = self.template_files.write().unwrap();
+            let mut templates = self.templates.write().unwrap();
+
+            templates.register_template_file(name, &path)?;
+            template_files.insert(name.to_string(), (mtime, path));
+
+            templates.render(name, data).map_err(|err| format_err!("{}", err))
+        }
+    }
 }

src/server/rest.rs

@@ -16,7 +16,6 @@ use serde_json::{json, Value};
 use tokio::fs::File;
 use tokio::time::Instant;
 use url::form_urlencoded;
-use handlebars::Handlebars;
 
 use proxmox::http_err;
 use proxmox::api::{ApiHandler, ApiMethod, HttpError};
@@ -312,7 +311,7 @@ pub async fn handle_api_request<Env: RpcEnvironment, S: 'static + BuildHasher +
     Ok(resp)
 }
 
-fn get_index(username: Option<String>, token: Option<String>, template: &Handlebars, parts: Parts) ->  Response<Body> {
+fn get_index(username: Option<String>, token: Option<String>, api: &Arc<ApiConfig>, parts: Parts) ->  Response<Body> {
 
     let nodename = proxmox::tools::nodename();
     let username = username.unwrap_or_else(|| String::from(""));
@@ -338,11 +337,11 @@ fn get_index(username: Option<String>, token: Option<String>, template: &Handleb
 
     let mut ct = "text/html";
 
-    let index = match template.render("index", &data) {
+    let index = match api.render_template("index", &data) {
         Ok(index) => index,
         Err(err) => {
             ct = "text/plain";
-            format!("Error rendering template: {}", err.desc)
+            format!("Error rendering template: {}", err)
         },
     };
 
@@ -580,15 +579,15 @@ pub async fn handle_request(api: Arc<ApiConfig>, req: Request<Body>) -> Result<R
                 match check_auth(&method, &ticket, &token, &user_info) {
                     Ok(username) => {
                         let new_token = assemble_csrf_prevention_token(csrf_secret(), &username);
-                        return Ok(get_index(Some(username), Some(new_token), &api.templates, parts));
+                        return Ok(get_index(Some(username), Some(new_token), &api, parts));
                     }
                     _ => {
                         tokio::time::delay_until(Instant::from_std(delay_unauth_time)).await;
-                        return Ok(get_index(None, None, &api.templates, parts));
+                        return Ok(get_index(None, None, &api, parts));
                     }
                 }
             } else {
-                return Ok(get_index(None, None, &api.templates, parts));
+                return Ok(get_index(None, None, &api, parts));
             }
         } else {
             let filename = api.find_alias(&components);